This is one of many articles in a series I’m writing to cover end-to-end encryption for everything you do in your digital life. I’ll cover encrypting your webmail and mobile e-mail in other articles.

For a primer on encryption, please read my article “Understanding Encryption” as it teaches VERY IMPORTANT concepts that you need to know before moving forward here.

Did you know that ALL E-Mail goes across the open internet in plain, raw, NON encrypted text? Well, all except e-mail that you explicitly encrypt, which this article will show you how.

Encrypting your E-Mail requires the following steps that we’ll cover individually to simplify the process:

Install the proper plugin for your E-Mail app.
Create your public/private key pair.
- Store your private key in a VERY secure place.
- Publish your public key for others to use.
- Import your keys into your E-Mail plug in.
- Import your friends public keys into your E-Mail plugin.

Since I obviously don’t have the resources to provide thorough instructions for every e-mail app out there and for every plugin available, I’ll cover 1 popular e-mail app and 1 popular plugin. The e-mail app we’ll be using for this tutorial is Mozilla’s Thunderbird, available on Windows, Mac, & Linux. You can download it here. It’s free and open source.

Since you’re reading this article, I’m going to assume you’re already using an e-mail program on your PC, or you wouldn’t be here, so I’ll skip the tutorial on how to install and configure an e-mail app. You should already have that up and going before continuing here.

First, you’ll need a plug in for your e-mail app that can handle encrypting and decrypting e-mail. I recommend Enigmail for Thunderbird. Click here to get it. It’s also free and open source.

Once installed (I assume you don’t need a tutorial to install the plugin), open the new “OpenPGP” menu in Thunderbird and select “Key Management”.

It’ll look like this:

If you already have a public/private key pair, add them here. You should have them in an .asc file.

If you do NOT already have a public/private key pair, inside the OpenPGP Key Management window, open the “Generate” menu and choose “New Key Pair”.

If you have more than one E-Mail address configured in Thunderbird, you’ll want to generate a new key pair for each e-mail address. Choose your e-mail address from the drop down list at the top of this window.

Choose a passphrase and don’t forget it. Also, for the love of all that is digital, DO NOT MAKE IT SIMPLE!!!! If you’re going through the effort of generating public/private key pairs to make it difficult for eavesdroppers to see your communications, don’t drop the ball now and use a short or easy password. I recommend using LastPass.com to generate long, complex passwords and to store them for you (fully encrypted, of course).

Choose an expiration date too.

Why choose an expiration date?

First, let’s explain what that is. After that date, all software to all other users will inform them that this is invalid.

Why you want this: If you forget your passphrase and your key becomes compromised, you’ll NEVER be able to revoke your key. Put an expiration date on it so that it will eventually die on its own.

I recommend 1 to 2 years. You can and should generate new keys when they expire and publish the new public key.

Once it’s all filled in the way you like it, click “Generate Key”.

Allow the software to generate a revocation certificate.

Now, backup and protect your private key. Store it in a safe place. I recommend storing it as a secure note in LastPass.com as well as inside of an encrypted virtual disk (I’ll explain this in a later article).

Publish your public key

Now, your public key is no good if no one has it. Remember, in order for anyone to send you an encrypted message, they MUST encrypt it with your PUBLIC key.

Right-click your key(s) and choose “Upload public keys to key server”. This makes your key available in search results on public key servers by anyone that knows your name or e-mail address.

If you ever accidentally expose your private key, you can revoke your key pair from this app by right-clicking your key and choosing to revoke it. Be sure to upload the change to the key servers so others know your key is revoked and they stop sending you important information encrypted with your old, public key.

You’re now ready to begin using encrypted E-Mail. BTW, click the “Display All Keys by Default” check box to see your key(s) listed there.

I recommend setting this up for all the members of your household on each of their PCs. Set each member up with their own private/public key pair and show them how to properly manage them or point them to this article and let them do it. Let THEM come up with the key phrases and ENSURE they don’t forget them! Then, you can start E-Mailing your family members securely.

Get public keys of your contacts

You can’t send encrypted mail to anyone until you have their public key. So, in the Key Manager app, open the key server menu and choose “Search for keys”. You can type partial or whole e-mail address or user names. It will search public key servers for any matches. There are 3 or 4 key servers provided in the key manager. If you don’t find your contact in one, try another. Of course, call your contact and make sure they even HAVE a public key. They can also e-mail it to you. Note: While testing the search while writing this article, none of the key servers found any address that I knew was there. Note that you can copy the URL from the search window and paste it into your address bar in your web browser and really search directly on those key server sites to find your contact’s keys.

Once found, add them to your key list (called a “key chain”). That makes them available to you when you send encrypted E-Mail. Speaking of which, let’s send some encrypted E-Mail now.

Send your first encrypted E-Mail

Close your key manager. Start a new e-mail message in Thunderbird. Address it to someone for whom you have a public key. Click the “OpenPGP” button. The first time you send an e-mail message, encrypted, from your e-mail address, Enigmail will prompt you if you want to enable OpenPGP for this identity. Be sure to check that box. I recommend checking the “Encrypt messages by default” check box too.

Click OK, then the dialog box pops up that you’ll likely see before sending each messages:

Click “OK” and your message will be encrypted and sent.

Side Note: “Signing” a message is important if you want to prove to the recipient that it’s from you. This is explained in my “Understand Encryption” article, which you should be familiar with.

Note that Enigmail will encrypt the message with the public key associated with the RECIPIENT’S E-Mail address, not YOURS.

See these images?

You’ll find actual working versions of them at the top and bottom of this article. Please click the appropriate buttons in it to let your friends know about this article.

The topic of encrypting is wide and deep, so I’ll narrow this discussion to the basics of what you need to understand about E-Mail encryption and I’ll be as concise as possible. This also begins a series of articles on encryption I’ll be writing over the next week or two explaining everything you need for end-to-end encryption for everything in your digital life from files on your mobile device to phone calls to everything on your PC. All software in my series will be free and open source.

Click here to follow me on Minds.com.

Encryption and Decryption

When you send an encrypted message to someone else, you must have that person’s public key. This is an encryption key that they publish on public key servers for anyone and everyone to have access to. These public keys can only encrypt messages. They cannot decrypt messages. If you encrypt a message with a friend’s public key, there is NO WAY you can decrypt it, not even with the public key you just used to encrypt it.

Why? Because the public key was created with a complex mathematical formula that actually created TWO keys that work together. Anything encrypted with ONE key can ONLY be decrypted with its pair key. When you use your friend’s public key to encrypt a message before sending it to them, ONLY your friend can decrypt that message and they must do it with their private key.

Conversely, when someone sends YOU an encrypted message, they MUST encrypt it with YOUR public key. ALL encrypted messages YOU receive MUST have been encrypted with YOUR public key.

YOU create a public/private key pair with a key generator. There are many apps that can generate key pairs. OpenPGP is a popular standard for keys. That simply means that software designed to encrypt or decrypt has been written for standardized encrypting algorithms. OpenPGP is a very popular algorithm.

When your friend sends you an encrypted message, encrypted with YOUR public key, only YOU can decrypt that message and ONLY with your private key that was created along with your public key.

Your public key is meant to be shared. That’s how people encrypt messages intended for you. Your private key is exactly that: Private. You MUST protect is and never, EVER give anyone access to it. This means do NOT store it on a cloud drive. Do NOT EVER e-mail it to anyone, not even yourself, because as soon as you hit “send”, it’s now passing through the internet, unencrypted. If you ever make the mistake of e-mailing your private key or storing it on a cloud drive, you should consider that key compromised. You’ll have to revoke the key and create a new pair. It’s now well known that the NSA intercepts all e-mail traffic. If you EVER e-mail your private key, there’s a nearly 100% chance that the government now has your private key and has the ability to decrypt any and all content encrypted for you with your public key.

Digitally Signing content.

A neat side effect of having public/private key pairs is that you can reverse how you use them. For example, instead of encrypting a message with people’s public keys, you could encrypt a message with your PRIVATE key. Under normal circumstances, you’d NEVER do this because 100% of the population has access to your PUBLIC key and ANYTHING encrypted with your PRIVATE key can be decrypted with your PUBLIC key.

So, why would you do this?

Simple, if you want to PROVE that a document was actually created or sent by YOU. Encrypting data with your PRIVATE key (instead of your public key) is called “Digitally signing” the content. Even though, mathematically, it’s the same thing as encrypting, in practice, that encryption is useless for secrets because the decryption key (your public key) is well known. But, just like data encrypted with your public key can only be decrypted with your private key, data encrypted with your private key can ONLY be decrypted with your public key.

So, if you ever want to prove you’re the sender of an e-mail message, you will digitally sign it before sending it (or encrypt it with your private key). The receiver can get your public key from any number of public key rings and decrypt your message, proving that it had to have been encrypted (or “signed”) with ONLY your private key.

Let me reinforce that “encrypting” with your private key is NOT considered “encrypting” since anyone can decrypt it. It’s considered “digitally signing”.

Got it? Good! Now, go encrypt all the things!

See these images?

You’ll find actual working versions of them at the top and bottom of this article. Please click the appropriate buttons in it to let your friends know about this article.

Check back later for updates too!

Next, be sure to read the next article in this encryption series:

Encrypt Your desktop E-Mail

Tag: public

Stick it to the NSA: Encrypt Your desktop E-Mail